Automatic telephone system



Dec. 5, 1939. LURK AUTOMATIC TELEPHONE SYSTEM Filed July 22, 1957 2Sheets-Sheet'l FEG.

INVENTOR. HANS JOACHIM LURK BY b ATTORNEY.

Dec. 5, 1939.

H. J. LURK AUTOMATIC TELEPHONE SYSTEM Filed July 22, 1937 FIG. 2

2 Sheets-Sheet 2 90x 91h 89d 8 F 541 92p 88 3 94p :2,5,8 1 '16 12'4654BUSY TONE INVENTOR.

HANS JOACHIM LURK ATTORNEY.

Patented Dec. 5, 1939 ATE AUTOMATIC TELEPHONE SYSTEM Hans Joachim Lurk,Berlin-Siemensstadt, Germany, assignor to Siemens & HalskeAktiengesellschaft of Wernerwerk, Siemensstadt, near Berlin, GermanyApplication July 22, 1937, Serial No. 154,977 In Germany August 4, 193613 Claims.

The present invention concerns a circuit arrangement for zone meteringin remote communication systems and more particularly in automatictelephone systems in which the zone is determined by numbers comprisingdifferent numbers of digits.

In such arrangements it is necessary to provide switching means whichrender impossible any further influencing of the zone characterizingdevices after the reception of the impulse train which completes thecharacterization of the zone. It may happen, however, that the zonecharacterizing devices are brought by impulse trains into positions overwhich no zone 1Q; determination can take place as can occur if the zonecharacterizing devices are set by numerical impulses which do notcorrespond to the prescribed characterizing digits. The determination ofthe zone can also be made impossible in the event of faults in the pathserving for zone characterizing (a break in the zone cable).

In order now to prevent an unnecessary setting oi the zonecharacterizing devices in such cases and to prevent as rapidly aspossible any further setting up of the call, switching means areassociated with the zone characterizing devices, according to theinvention, which directly after the impulse train by which the zonecharacterizing devices are either brought to a position enabling thezone to be determined or are brought to a position which does not allowof such a zone determination, either enable the establishment of thecall to proceed in the one case or prevent it in the other case, whilein 1 both cases preventing any further influencing of the zonecharacterizing devices.

An embodiment of the invention is represented in the drawings,comprising Figs. 1 and 2.

The main parts of the repeater shown are as follows:

1) Rotary switch DG.This rotary switch is set in a definite manner bythe first numerical impulse train transmitted by the calling subscriberand operating on the repeater. According to the number of digitsnecessary for determining the zone of the call a wiper of this rotaryswitch is either directly connected toa zone contact or a wiper of atwo-motion switch is connected up by a wiper of this rotary switch.

(2) The two-motion switch.The two-motion switch with its vertical magnetHH and its rotary magnet DD is set by the second and third impulse trainoperating on the repeater. In particular cases it takes up a fourthdigit.

(3) The time switch DZ.-The time switch (01. 179-'7.1) I v is influencedby a time switching device which operates so that it receives a steppingimpulse every minute. The time switch determines in the presentembodiment the moment for transmitting a definite number of meteringimpulses.

(4) The assessor DA.-'The assessor is advanced by steps when the momentarrives for transmitting metering impulses, the stepping be ingcontinued until one of its wipers finds a zone contact characterized bya particular potential. On each step metering potential is applied overone of the speaking leads and in this way the calling subscribers meteris advanced a definite amount. The assessor serves moreover to registerthe small units of time. It is under the in fluence of a five or tenseconds contact and registers these time impulses until a largerinterval of time, namely a minute, has elapsed. The minute units arethen taken up by the time switch DZ as previously mentioned.

The mode of operation of the devices shown will now be described indetail.

Setting the zone characterizing devices.The seizure of the repeatertakes place over the clead in which is disposed relay 0. Relay C isenergized. Relay C closes contact 310 and thereby completes thefollowing circuit: earth, contact 3|c, 25k, 2st, ZIww (rotary off-normalcon tact operated when the two-motion switch is in its operatedposition) 2970 and 3012, wiper dg5 in the rest position, winding I ofrelay E, battery and earth. In this circuit relay E energizes and byclosing its contact l25e connects the impulsing contact l28a to themagnet of the rotary switch DG. When now a numerical impulse train istransmitted by the calling station relay A is energized impulsively in'the following circuit by the impulsive application of earth to the upperspeaking lead in the preceding connecting device: earth in the precedingconnecting device. upper speaking lead, contact 69, winding I of relayA, battery and earth. Through the impulsive closing and opening ofcontacts iiliia and 16a earth is connected to the upper speaking lead oneach impulse so that impulses are transmitted to the subsequentconnecting devices over contact lll'ls corresponding to the impulsesreceived and these serve to set these connecting devices. Through theimpulsive closing of contact Ed the following circuit is completed forrelay V: earth, battery, windings I and II of relay V, contact 5a andearth. When it energizes for the first time relay V closes contact 4vand thus short-circuits its winding II. It is thereby madeslow-to-release and this suifices to hold up the contacts of relay Vduring the individual impulse trains. The rotary switch DG is now set bythe impulsive closing of contact 1280., the magnet being operated overthe following circuit: earth, contacts l597c, l28a, l2'isl and I256, themagnet of the rotary switch DG, battery and earth. The wipers of theswitch DG are thus brought to a particular contact. Although wiper dg5has left its rest position relay E remains operated throughout theimpulse train in the following circuit: earth, contacts I510, I561),l55e and l54m, winding III of relay E. battery and earth.

If the zone is determined merely by the first numerical impulse trainoperating on the repeater the wiper dgZ stands on one of the contacts lto 5, l to 9 which is connected directly to one of the zone contacts ZoIto ZoV. If in particular cases the zone is determined by two impulsetrains operating on the repeater a further setting of the rotary switchtakes place in accordance with the second impulse train received. -Thenecessary requirement for this is that the first impulse train shallhave brought the wipers of the rotary switch into position 6. Afterrelay V has released on account of the prolonged opening of contact 5aafter the impulse train comprising six impulses the following circuit isestablished over wiper dg5: earth, contacts 3lc, 257e, 26t, Z'lww, 29kand 3012, wiper (195 in position 5, windings III of relays T and Q,battery and earth, and winding I of relay 0, battery and earth. Afterthe first impulse train the locking circuit for winding III of relay Eis broken by the opening of contact I561) so that rela 1 E releases.Since, however, relay T has been energized in the circuit just describedthe impulse train which now follows is trans mitted to the magnet of therotary switch DG over contact IZSt, while an undesired setting of thevertical magnet I-IH of the two-motion switch which was connected upwhen contact |24e closed is prevented by the opening of contact I 221i.The second impulse train is thus trans mitted to the magnet of therotary switch DG over the following path: earth, contacts I59k, iZBa,I213! and [2615, the magnet of the rotary switch DG, battery and earth.At the end of this impulse train relay T releases again, this being aslow-release on account of the construction of the relay. Relay Q alsoremains up until after the end of the impulse train and also until theend of its natural release period, over the circuit: earth, contact 9aor lilo, lq, winding II of relay Q, battery and earth. Wiper dgZ isdisconnected by contact 4415 and wiper dg3 is connected up through theclosing of contacts Hi and 461 The zone contact is thus reached in thepresent case over wiper dg3 whose contacts are connected to the zonecontacts ZoI to ZoV in a particular manner.

If the zone is not to be determined until the third impulse trainoperating on the repeater has been transmitted the rotary switch DG isbrought to position 0 by the first impulse train operating upon it, i.e., the impulse train comprises ten impulses. In this case relays T andQ cannot energize. As already mentioned relay E releases a short timeafter the termination of the first impulse train (through the opening ofcontact i561. Contact l25e is thereby opened and the magnet of therotary switch DG is disconnected and the vertical magnet H of thetwo-motion switch is connected up by the closing of contact I2 4 e, Thesecond, impulse train operating on the repeater is thus repeated to thevertical magnet HH over the following circuit: earth, contacts l59lc,l28a, l21sl, 124e, IZZt, ll9u, IZOww (off-normal contact which is openedafter the first rotary step of the two-motion switch) vertical magnetI-II-I, battery and earth. The wipers of the two-motion switch, of whichonly the two wipers full and hdZ are shown, are thus raised to aparticular level. The contact field of the two-motion switch isindicated by dotted squares adjacent the wipers hdi and M12 for the sakeof simplicity. Since the oii-normal contact 22lck is closed after thefirst vertical step of the two-motion switch the following circuit isset up when relay V releases: earth, battery, winding I of relay U,contacts llc, l8g, 2w, 22kk, Z'l'ww (rotary off-normal contact of thetwo-motion switch opened after the latter has taken the first rotarystep), 262?, 25k, 3lc and earth. In this circuit relay U energizes. Whennow the third impulse train is received relay V is energized throughoutthis impulse train. Consequently contact 201) is closed therebycompleting a locking circuit for relay U: earth, contact ISu, 20v, lBg,and He, winding I of relay U, battery and earth. During this impulsetrain, contact H911 is opened so that the vertical magnet I-II-I isdisconnected and contact H811. is closed thereby switching in the rotarymagnet DD of the two-motion switch. The third impulse train operating onthe repeater accordingly operates the rotary magnet of the two-motionswitch, this taking place over the following circuit: earth, contactsl597c, l28a, I21sl, I246, I222? and Ba, rotary magnet DD, battery and.earth. In the level to which the switch has been set the wipers areaccordingly brought to a particular contact. On the termination of theimpulse train relay V releases and releases relay- U by opening contact2011-. The contacts of the two-motion switch are wired to the zonecontacts ZoI to 20V in a particular way.

According to the embodiment it is also possible to determine the zoneonly after four impulse trains have operated on the repeater. If, forexample, the first impulse train operating on the repeater comprises tenimpulses, wiper 1192 is brought to position In., If then the twomotionswitch is stepped to the sixth level and then set on the fourth contactin the sixth level the wipers hdl, hd2, stand on a line characterized bythe number 64. After relay V releases after the third impulse trainoperating on the repeater the following circuit is completed: earth,battery, winding I of relay Q, line 64, wiper hdl, contact 42a (relay Uremains up after relay V has released because it is made slow-toreleaseto a certain extent through the shortcircuiting of its winding II),contact dllq, contact l0, wiper c192. contacts 3814, Mt, 3912, 31c andearth. Relay Q opens its contact Mlq, breaks the circuit just mentionedand closes contact 48q, whereby the following locking circuit isestablished for relay Q independently of the contacts of relay U, overwiper hd2: earth, battery, Winding I of relay Q, line 64, wiper hdZ,contacts 48: Ht, 391) and 310 and earth. Relay Q closes its contact l2lqwhereby the next impulse train is also transmitted to the rotary ma netDD of the two-motion switch in spite of contact H814 being open: earth,contacts l59k, IZBa, l2lsl, I24 l22t and l2lq, magnet DD of thetwo-motion switch, battery and earth. During this impulse train relay Qholds up over its winding II in a circuit which has'already been setout. The characterization of the zone (setting on a particular zonecontact) now takes place over wiper hdZ of the two-motion switch whosecontacts are connected to the zone contacts 201 to 20V in aparticular'way.

The characterization of the zone by four impulses trains operating ontherepeater can be efiected in an alternative manner. If, for example,impulse trains corresponding to the number 066 are sent into therepeater wiper hdl of the two-motion switch will stand on line 56 sothat after the release of relay U and during the release period of relayU the following circuit is closed: earth, battery, inding I of relay T,line 66, wiper hdl, contacts 42a and lllq, wiper dg2, contacts 38a, Mt,39v and Zlc and earth. In this circuit relay T energizes and by openingits contact Mt disconnects wipers hell and M12 of the two-motion switchand by clos ing contact 45f connects wiper dot of the rotary switch DG.The following locking circuit is established for relay T: earth,battery, winding I of relay T, level contact 49dk6 (closed when thetwo-motion switch is set on level 6), contact Ill, wiper dg i, contacts-i'lq, 45 39v and 3|c and earth. During the impulse train which nowfollows relay T holds up over its winding II in a circuit which haspreviously been described. The fourth impulse train received by therepeater is now also taken up by the rotary switch DG whose magnet isoperated by contact l26i: earth, contacts IESk, l28a, l2'ls i and 126i,the magnet of the rotary switch DG, battery and earth. Thecharacterizing of the zone now takes place over wiper 194 of the rotaryswitch DG over a contact of the latter which is directly connected toone of the zone contacts ZOI to 20V.

ZONE CONTROL For each of the numerical impulse trains operating on therepeater the zone control sets in automatically: i. e., switchingoperations are pro- (a) Zone control after the first impulse trainoperating on the repeater- The rotary switch DG is set so that itswipers do not rest on contacts 6 or Ill. By the setting of the rotaryswitch DG in accordance with another digit the zone is characterizedsolely by this first impulse train operating on the repeater. After therelease of relay V the following circuit v for relay K is set up: earth,battery, winding I of relay K, one of the contacts 'l9k, 80k, Slk, 82kor ask, one of the zone contacts ZOI to ZoV, wiper 11912, in a positionother than 6 or HI, contacts 368, Mt, 38v, and 3H: and earth. Relay Kenergizes and by opening its contact I59k brings the influencing of thezone determining devices by numerical impulse trains to an end.

Relay K locks up over the following circuit throughout the duration ofthe call: earth, battery, winding II of relay K, contacts 24k and Mo andearth. Contact 31k maintains the earth connected over contact Elcconnected to wiper dot and the corresponding zone contact.

It may be mentioned that relay X is energized over the following circuitduring each impulse train: earth, contacts 61c, 69c and 68p,

windings II and I of relay X, contact 65h, re-

sistance Wil l, battery and earth. Relay X closes its contact 6611: andthereby short-circuits its winding I so that after relay V has releasedand contact 6911 has opened it retains its contacts in the operatedposition for a short time. After the release of relay V and the closingof con tact 3912 it is possible for relay K to energize. If, however,this isnot possible on account of the presenceof a fault in the zonelead relay S energizes after relay X has released, in the followingcircuit: earth, battery, the-winding of relay S, contacts q and 34x,wiper dgl in a position other than 0, 5 or II], contacts 261?, 25k and3lc and earth. If, therefore, the zone circuit cannot be exerted'in-apositive sense relay S energizes and by opening its contacts I015 and[68s disconnects the stepping leads and renders the further setting ofconnecting 'devices impossible. Relay SI also energizes and at contactI218! disconnects contact 128a. Through the closing of contact lfiis abusy signal is applied to windings II of relays A and F and is inducedin the windings -I of these relays which are connected to the speakingleads and is thus transmitted to the calling subscriber. Winding I ofrelay F is connected over contact 3g and a condenser to the lowerspeaking lead and winding I of relay A to the upper speaking lead overcontact to. The relays S and SI hold up in the circuit set out aboveuntil the calling subscriber replaces his receiver on account of theprolonged busy signal and transmits the signal for the release of thedevices which have been set.

(1)) Zone control after two impulse trains have operated on the repeaterIn this case' the calling subscriber transmits an impulse traincorresponding to the number 6 as the first impulse train. Wiper (195 isthus set on contact 6, over-which relays T and Q are energized overtheir windings III and relay 0 over its winding I after relay V hasreleased. After this impulse train relay K cannot yet energize becausecontact. 6 of the rotary switch is not connected to any of the zonecontac-ts 201 to -ZOV. Similarly the blocking relay S cannot energizebecause this is disconnected by contact 35g. Thus although the zonecontrol relay K cannot energize after the first impulse train theblocking of the connection by relay S is also prevented. Only when therotary switch DG has received a further impulse train is the followingcircuit set up for relay K: earth, battery, winding I ofrelay K, one ofthe contacts 19k: to 83k, one of the zone contacts ZoI to ZOV, a contactin the contact bank associated with wiper dg3, wiper dg3, contacts 461st, 3912 and Bio and earth. When relay K energizes in this circuit,contact lZlc and the two relays Q and T remain energized in thefollowing circuit until the end of the call: earth, contacts 80, 12k andMq, winding II of relay Qand contact l5t, winding II of relay T, batteryand earth. After relay K has energized and locked up at contact .24k aparticular zone contact is connected to earth over contact 3lc by way ofwiper (Z93 and contacts 45t and 46g.

If, however, relay K is not able toenergize in the above circuit onaccount of a break in the zone lead or because a false second number hasbeen dialled whereby wiper dg3 is set on a contact which is notconnected to a zone contact, no locking circuit is set up for relays Qand T so that after relay X has released the following circuit isestablished for the blocking relay S: earth, battery, the winding ofrelay S,

contacts 35q and 34x, wiper rlgl, contacts 2% h connected to the othercontacts of this contact bank. As already described relay was energizedover its winding I when wiper (105 was set on contact 6. Relay 0 looksup in the following circuit: earth, contacts to and I370, winding II ofrelay 0, contact 230, battery and earth. This locking circuit remains inexistence until the clearing signal is given if the zone controllingrelay K cannot energize. In this case the following circuit is closedfor the blocking relay S:

earth, battery, winding of relay S, contacts 351! and 36x, wiper 1191 inposition I0, contacts 330,

26t and 25k, 3Ic and earth.

(0) Zone control after the third impulse train operating on the repeaterAfter the rotary switch DG has been set on the th contact the wipers ofthe two-motion switch stand on some line which is not especiallyindicated (but not on lines 64 and 66) after the next two impulsetrains. After relay V has released at the end of the third impulse trainopcrating on the repeater, the circuit for the zone control relay K isset up over wiper hall and wiper (192 in position III, the circuit beingset up over contact 3811. of relay U which maintains it contactsoperated after the release of relay V. Relay K locks up as before atcontact 2479 throughout the duration of the call and at contacts 31k andMia maintains the connection of earth to the corresponding zone contact.

If for the reasons mentioned above the circuit for relay K is notcompleted the blocking relay S and relay SI become energized in thefollowing circuit after relay K has released; earth, battery, thewindings of relays S and SI, contacts 35q, 34m and 28ww (rotaryoff-normal contact of the two-motion switch which is closed when theswitch takes its rotary step). contacts 251, 25k; and Mo and earth.Relay S initiates the operations already described for preventing thefurther establishment of the call and for communicating a busy signal tothe calling subscriber, while relay SI prevents the zone characterizingdevices from being influenced by further numerical impulse trains atcontact IZIsI.

(d) Zone control after the fourth impulse train operating on therepeater If the two-motion switch is set on line 64 relay Q is energisedas already stated and this disconnects wiper hill of the two-motionswitch at contact 40g and connects up wiper hcl2 by closing contact 48g.During the fourth impulse train operating on the repeater, which is alsoreceived by the rotary magnet DD, of the twomotion switch, relay Qremains operated over its winding II for some time after relay V hasreleased at the end of the fourth impulse train. Thus the wipers of thetwo-motion switch stand on a particular line (not shown) which isconnected to one of the zone contacts ZOI to ZoV.

During the release period of relay Q the zone control relay K is testedas to its ability to energize, in the following circuit: earth, battery,winding I of relay K, one of the contacts 19k, to 8310, one of the zonecontacts ZOI to ZOV, wiper hd2 of the two-motion switch, contacts 48q,Mt, 39v and 3Ic and earth. The blocking relay S is not able to energizebecause contact 2570 is open. If, however, relay K does not energizewithin the release period of relays Q and X a circuit which may be seenfrom the drawing is once more set up for the blocking relay S.

If the two-motion switch is brought by the third impulse train operatingon the repeater to line 66, relay T is operated as already explained andthis holds up over its winding II during the following fourth impulsetrain until the end of this train, when relay V releases. At contact 44tthe wipers of the two-motion switch are disconnected and wiper (Z94 ofthe rotary switch DG- is connected up at contact St. The wipers of therotary switch DG are stepped further by the fourth impulse train, sothat wiper (Z04 is set on a contact which is connected to one of thezone contacts ZoI to V. When relay V releases at. theend of the fourthimpulse train the zone control relay K is tested as to its ability toenergize in the following circuit: earth, battery, winding I of relay K,one of the contacts 19k to 8370, one of the zone contacts ZoI to ZoV,

wiper do l set on a particular contact, contactsclq, 4st, 39v and 3Icand earth. If relayK cannot energize during the release period of relayX, the circuit for the blocking relay S and forrelay SI is again closed.

The wanted subscriber replies When the wanted party replies after allthe ing lead in one of the succeeding connecting devices. Thus thefollowing circuit is established: earth, battery in the succeedingconnecting devices, the lower speaking lead, contacts I08s and. H2112,winding II of relay Y2, contacts Hi9 and Itlllc and earth. Relay Y2which energizes in this circuit at contact H2112, breaks the previouslyexisting short-circuit for winding I of relay G so that this relay canenergize in the above-mentioned circuit. Relay G closes its contact IIIlg and thereby locks up over earth, con- 5: tacts Ill9k and H09,winding II of relay G, battery and earth. Through the opening of contactIII g it breaks the above-mentioned circuit. Through the closing ofcontact I349 the following circuit is closed for the switch DA whichresponds to the small units of time of five or ten seconds: earth,battery, the magnet of switch DA, contacts I290, I358, I31m, and I396,the fiveseconds contact and earth. Relay E was operated over its windingIII in the following circuit: earth, contact I5Ik, wiper da3 of theassessor in position 0--I, winding III of relay E,

battery and earth. The assessor consequently receives five secondsimpulses and steps its wipers at intervals of five seconds. When wiper(1113 ,has left contacts I] and I relay E releases and by closing itscontact I38e switches on a 10 seconds contact in place of the fiveseconds contact so that now the assessor is advanced at intervals of 10seconds.

.III

When after the expiry of"75.

'III

-' contacts cuit for relay YI.

about a minute the wipers of the assessor reach contact 9 the assessorcommences to pass automatically to the zero position. This occurs in thefollowing manner: When wiper daI reaches the ninth contact the followingcircuit is completed: earth, battery, magnet DA of the assessor, contactI290, contact 9, wiper daI, the winding of relay R, contacts I4Eu,I4'Ih, I49y2 and earth. Relay R which energizes in this circuit closesits contact I9r and thus completes the following circuit for relay U:earth, contact I91, winding II and I of relay U, battery and earth. Bythe opening of contact I46u the above circuit in which magnet DA andrelay R were energized is broken. The assessor magnet DA and also relayR release, so that the circuit for relay U at contact I91 is brokenagain. Magnet DA and relay R are again operated by the closing ofcontact I46u. The interaction between relays U and R continues untilwiper daI has left its last contact and has passed into the restposition. The following circuit for the magnet DZ was closed over wiper(M3 in position 9: earth, contact I5Ik, wiper da3, position 9, contactI52x, magnet DZ of the time switch, battery and earth. The time switchaccordingly advances its wipers from the rest position to the firstcontact. The following circuit then obtains for relay M: earth, battery,winding I of relay M, contact I, wiper d2! of the time switch, contactsH09 and I99]; and earth. Relay M holds up throughout the duration of thecall in the following locking circuit: earth, battery, winding II ofrelay M, contacts IIm, I2k and 8c and earth. When the circuit alreadymentioned for winding III of reiay E is closed again when wiper da3moves into the rest position the 10 seconds contact remains connected tothe assessor magnet because of the closed contact I3Sm. When now afterexpiry of the second minute the wipers of the assessor pass to positionI the play between relay R and U sets in once more, relay R beingenergized together with the assessor magnet in the following circuit:earth, contacts I49y2, M171. and Him, the winding of relay R, wiper dalin position 1, contacts I32m and I290, magnet DA of the assessor,battery and earth. The assessor is thus switched back to its normalposition. On passing through position 9 the circuit previously mentionedfor the time switch DZ was again closed so that the wipers of the timeswitch are set at contact 2. The third minute of the conversation nowcommences. When the switch passes to position 5 under the influence ofthe 10 seconds contact relay Z energizes in the following circuit:earth, battery, the winding of relay Z, contact l30y4, contact 5, wiperdaI, the winding of relay R, contact I4'Su, I4'Ih and I49y2 and earth.Relay Z closes its contact I022 and thereby completes the followingcircuit for relay Y3: earth, contacts I99lc, IIlIg and I022, winding IIof relay Y3, battery and earth. Relay Y3 closes its contact IIlIy3 andthereby completes the following circuit for relay YI: earth, I99k,IIllg, lull/3, winding I of relay YI, battery and earth. RelayYI causesrelay Y2 to energize over its winding I by closing contact IIlDyI. Thisbattery relay by closing its contact 98112 switches on relay Y4 overearth, contacts W970, H09 and 98y2, the winding of relay Y4, resistanceWiI3, batttery and earth. The opening of contacts ISM/4 and 962/4disconnects the circuit of relay Z. Relay Z at contact l02z opens Y3.Contact IIIIy3 breaks the cir- Relay YI disconnects the time switch passto position 3.

circuit of relay Y2 atcontact [001/1 so that the latter relaydeenergizes. Relay Y2 closes its con- ,tact 99M and therebyshort-circuits the winding'of relay Y4 so that in spite of its lockingcontactQ'IM, relay Y4 is caused to deenergize. For the period betweenthe operation of relay Z and the release of relay Y4 a warning si nal istransmitted to the calling subscriber shortly before the expiry of thethird minute of the conversation, in that the following circuit isestablished: buzzer Su, contact I642 or I65y4, wiper d22 set on contact2, contact I62s, winding II of relays A and F, wiper 01103 in one of thepositions 5 and 8, contact I5Ilc and earth. The buzzer tone istransmitted inductively to windings I of relays I and A in the speakingleads and hence to the calling subscriber. Winding I of relay A is nowconnected over contacts 1g and a condenser to the lower speaking leadand winding I of relay F to the upper speaking lead over a condenser andcontact 59. During the release period of relay Y4 which wasshort-circuited after the release of relay Y2 the assessor is advancedfrom. position 5 to position 6: earth, battery, magnet DA of theassessor, contacts I290 and I.3Iy4, wiper (MI in position 5, 'thewinding of relay R (which does not energize in this circult) contactsI46u, M171. and M9212 and earth. After a further 10 seconds the wipersof the assessor are brought. to contact I from which they are advancedto the zero position by the aid of the relay interrupter RU in themanner already described. When wiper da3 passes through position 9 thecircuit for the time switching relay DZ is again closed so that thewipers of the The following circuit for relay X is now completed overwiper o'el of the time switch: earth, contacts I09Ic and H99, wiper dzin position -3, contacts He and 68p, windings II and I of relayX,'contact 65h, resistance WiI I, battery and earth. When the assessormoved into position I3 the following circuit is set. up for relay I-I:earth, battery, winding I of relay I-I, contact I593), wiper (m3 of theassessor in position I3, contact I5Iic and earth. Relay I-I locks upover earth, battery, winding II of relay H, contacts 9Ih, 921), M09 andI097c and earth. Relay H opens contacts 85h andthus breaks the circuitjust described for relay X which accordingly releases.

Metering for the first unit of time lead over a series of resistance andchoke-coils: earth, battery, resistance WiII, choke-coil DT3, contact598I, resistances Wzfl, Wi'I, WiG, W 5, W14, W13, WM and. WiI, chokecoilDTI, lower speaking lead. On account of the various resistances and thechoke-coils the application of the metering potential by com tact 64h tothe lower speaking lead is damped so that the subscriber engaged inconversation is disturbed as little as possible. Through the closing ofcontact Ihthe assessor magnet DA receives a stepping impulse over thefollowing path: earth, battery, assessor magnet DA, contacts I290, I349,IMIII, I42p, I44y4, I45h, I49y2 and earth. The assessor magnet possesesacontact 89da which is now closed and by means of which the followingcircuit is established:

contact 54h.

earth, battery, winding II of relay Y3, contacts The circuits are asfollows: earth, contacts l09x, H09, and H3 W3, winding I of relay Yl,battery and earth and: earth, contacts H1916, my, 96214, 95, 13, thewinding of relay Z, battery and earth. By closing its contact lllfiylrelay YI energizes relay Y2, By the closing of contact 98y2 relay Y4 isenergized and thus locks up by closing contact fill/4. Through theopening of contact 96114 the above-mentioned circuit for relay Z isbroken and this consequently releases. After relay Z relay Y3 releases,the winding 11 of this relay having been disconnected meanwhile atcontact llgda. After relay Y3 relay Yl releases, after relay Yl relay Y2and after relay Y2 relay Y4, all being short-circuited.

The above-mentioned operations are now repeated because the circuit forthe assessor magnet DA which was opened at contact Mflyd when relay Y4energized is completed again at this contact after relay Yl hasreleased. The assessor magnet is advanced a further step and by closingits contact 89cm causes the switching on of relays Y3, X, Yl, Y2 and Y4in the manner described above.

- Each time these relays perform this set of operations a meteringimpulse passes over the'lower speaking lead to the metering relay in thepreceding connecting device in that the individual resistance Wz'i toWz'S are short-circuited in succession by the contacts of the abovementioned relays and on the subsequent releaseof the relays are switchedin again in the succession Wil to W2'8. Each of said relays possesscontacts which draw up and release at moments displaced from one anotherin time so that for example contact 50y! is closed before contacts 5ly2,52y! before 54yl, 55113 before 563 3, and 5'52 before 582. Thus theabove-mentioned contacts are closed in succession and in this Way themetering potential connected to the lower speaking lead is graduallyincreased to an extent which suflices to energize the metering relayconnected to the lower speaking lead in the-preceding connecting device.On the subsequent release of these relays at the end of each meteringimpulse, the resistances Wil to W18 are gradually switched in and thecurrent over the lower speaking lead is gradually reduced again so thatthe metering relay in the preceding connecting device can release. Onaccount of the gradual switching in and switching out of the resistancesand by the gradual application and disconnection of metering batterysubscribers engaged in conversation are disturbed as little as possible.For each step of the assessor one metering impulse is transmitted overthe lower speaking lead. The number of metering impulses to betransmitted at the end of every three minutes interval is determined bythe setting of the zone characterizing devices, 1. e., by the setting ofthe rotary switch DG and of the two-motion switch I-II-I/DD. Over thewipers of these switches a particular zone contact ZoI to ZoV isconnected to earth as previously described. As has been mentioned, relayH, which determines the moment for commencing metering, is energizedwhen wiper daS passes through position l3. The transmission of meteringimpulses accordingly only commence when the Wipers of the assessor havereached contact l4. If, for example, the zone characterizing devicesconnect the zone contact 201 to earth, as many metering impulses aretransmitted as there are steps necessary in order to bring wiper da2from position I4 to that position to which the zone contact 201 isconnected. In theexample shown this wouldbe two impulses. After thetransmission of two metering impulses the following circuit obtainsduring the release period of relay Y4 which is the last of the relaychain to deenergize: earth on zone contact ZoI applied by the zonecharacterizing devices, wiper da2 on contact l6 contacts 1511i, Nye andI lit, the winding of relay P, battery and earth. Relay P at contactM217 breaks the stepping circuit for the assessor magnet DA which wasclosed during the transmission of metering impulses. At contact 9473 itlocks up over earth, battery, the winding of relay P, contact 12c,resistance Wii2, contacts 94p, (66g and N970 and earth. By the openingof contact 92p the above-mentioned locking circuit for relay H whichdetermines the commencement of metering is broken so that this relayreleases. The result of this is that contact M'lh. is closed andconsequently a circuit is completed which circuit contains the relay Rand the assessor magnet DA. The interaction of relays R. and U by meansof which the assessor is restored to normal now sets in once more. Whenthe assessor has reached its normal position relay E is ope-rated againover winding 3 and by opening contact 122 breaks the locking circuit forrelay P and thus causes this to release. This terminates the meteringfor the first 3 minutes interval. switch the assessor magnet DA is nowstepped around again and the second 3 minutes interval commences, andafter the expiry of 6 minutes the second transmission of two meteringimpulses takes place in the manor described.

It may be mentioned that after the lapse of each interval or 3 minutes,i. e., when the wipers of the time switch DZ are set in positions 3, 6,9, etc., relay E is held energized over its winding 3 during thefollowing time unit of 1 minute. So long as wiper da3 stands on contactsand I relay E is energized in a circuit which has been mentionedearlier. In positions 2 to 4 of the assessor DA, E is energized asfollows: earth, contact-s I5Ik, wiper (M3 on contact 2, 3 or 5 overcontacts 0, 3, 6, 9, l2 of the bank associated with wiper (Z23, contact"56m, winding III of relay E, battery and earth. In positions 5 and 6 ofwiper da3 relay E is held energized over the following circuit: earth,contact l5llc, wiper da on contact 5 or 6, wiper 0123 on one of thecontacts 3, 6, 9, etc., contact Hillm, winding III of relay E, batteryand earth. By this means so long as wiper clzl stands on one of thecontacts 3, i3, 9, etc., any undesired operation of relay X at contactTie and any consequent premature energizing of the relay H whichpromotes metering at contact I503: is prevented.

It can be seen directly from the drawings that if another zone contactis connected to earth over the zone characterizing devices, a differentnumber of metering impulses is transmitted. If, for

Under the influence of the 10 secondexample, the zone contact ZoII wereconnected to earth then 6 metering impulses would be transmitted. aftereach 3 minute interval in the case of such a call. If the zone contactZoIII were connected up 10 metering impulses would be transmitted, inthe case of zone contact ZoIV 14, and in the case of zone contact 20V 18impulses for every 3 minute interval.

When the calling subscriber hangs up on finishing his conversation,battery potential is applied to the upper speaking lead in the precedingconnecting deviceso that the following circuit is set up for relay F inthe repeater: earth, battery in the preceding connection device, upperspeaking lead, contacts 59*, Ma, winding I of relay F and earth. Relay Fcloses its contact if and thereby completes the following circuit forrelay X: earth, contacts T07, 6810, windings i2 andi of relay X,contacts 65h, resistance Wil I, battery and earth. Relay X closes itscontact thereby brings the assessor magnet DA under the influence of therelay interrupter. With the aid of relays R and U the assessor isadvanced until, in position I3 a circuit which has already been givenfor relay H is set up over wiper daI-l. Relay H locks up at contact SH].and by opening contact 54711. interrupts the interaction between relaysU and R. The assessor'magnet DA receives a stepping impulse over thefollowing path through the closing of contact MEh: earth, contactsI49y2, I457, i l ly l, M21), I lIr (relay X was deenergized by relay Hat contact 65h), I349, I290, assessor magnet DA, battery and earth. Theassessor magnet operates its contact 89da so that the following circuitis set up: earth, battery, winding II of relay Yi, winding I of relaySI, contacts 88y3, 87 885m, 981;, 9Ih, 92p, I109, I09k and earth. Inthis circuit relays YI and SI energize. Relay SI locks up over: earth,battery, winding 11 of relay SI, contacts 32s'l, 3Ic, and earth. Throughthe opening of contact 59sI the resistance chain WiI-WiB is disconnectedand by the closing of contact SilsI the full strength of the meteringbattery is applied directly; while eliminating the resistance chain, tothe lower speaking lead: earth, battery, resistance WiI I, contact 64h,choke-coil Dr3, contacts BilsI, 6Iy4 and 62yi, choke-coil Drl, and thelower speaking lead so that the metering relay in the precedingconnecting device will immediately energize and cause the meter to beadvanced. Relay YI closes contact Iflllyl thereby switching on winding Iof relay Y2. At contact 98y2 relay Y2 switches on relay Y4 which looksup by closing contact 91114. Relay Y4 opens contact I My I and therebybreaks the circuit for the assessor magnet DA. By the opening of contact89da the circuit over which relays YI and SI were energized is broken sothat relay Y releases. Relay SI holds up over its winding II. At contactIIJByI relay YI breaks the circuit for relay Y2 so that contact 99112 isclosed and relay Y4 is short-circuited. The stepping circuit for theassessor magnet is thus closed again at contact IMy I so that the cycleof operations is started afresh. During each cycle the metering impulseis started up by the closing of contact 82g! and terminated by theopening of contact El 4. In this way a corresponding number of impulsesis transmitted at a relatively more rapid rate. Thus on metering at theend of the call only the relays YI, Y2 and Y4 of the group Z, Yi-YI areused. The transmission of metering impulses is terminated when wiper daZpasses into a position which is connected to earth over one of the zonecontacts ZoI to ZoV and over the zone characterizing devices, as hasalready been explained in detail. The metering terminating relay Pdisconnects earth from the upper speaking lead by opening its contactip, this being the signal that the preceding connecting device isreleased. Relay F in the repeater continues to hold up for the moment ina local circuit: earth, battery, resistance Wis, contacts I f, and 2p,winding I of relay F and earth. Relay F holds up until relay P releasesafter the end of the metering and when the repeater is released. Throughthe disconnection of earth from the upper speaking lead the c-lead inthe preceding connecting de- M-ila: and I vice is broken so that relay Cin the repeater releases.

Restoration of the switches in the repeater In this circuit in additionto 10 The time switch is then brought to normal. ,15

The following circuit obtains: earth, contacts M9112, I4Ih, Mtu, windingof relay R; contact I580, wiper dot, in the rest position, wiperdz l inthe working position, magnet DZ of the time switch, battery and earth.The time switch is .20

stepped by the relay interrupter RU until it has reached the normalposition. Thereupon the two-motion switch is restored to normal. Thefollowing circuit obtains: earth, contacts HEE /2, Ifllh and Mia,winding of relay R, contact I580, wiper (296, in the rest position,wiper de l in the rest position, off-normal contact IIIlclc (closedafter the first vertical step of the two-motion switch), rotary magnetDD of the two-motion switch, battery and earth.

The rotary magnet is stepped until the rest position is reached underthe influence of the relay set U/R. Y

Finally the assessor is restored. The following circuit obtains: earth,contacts M9112, I4Ih,

M5141, winding of relayR, contact i580, wiper (96 in the rest position,wiper dad in the rest position, off-normal contact IIBkIc, (closed whenthe two-motion switch is in the normal position) wiper dad in theworking position, magnet DA of the assessor, battery, earth; When theassessor has. reached the normal position under the influence of therelay set U /R this circuit is broken at wiper daA.

Through the release of relay C the other switching devices are alsorestored to normal. The locking circuit for relay M is broken at contact8c'and the locking circuit for relays SI and K at contact 3Ic. Similarlyat contact 80 the locking circuit for relays Q and T is broken. providedthese have been energized. The locking circuit for relay P is broken atcontact limit, At the same time, at this. contact, the locking circuitfor relay G is broken. After relay P has released the locking circuit ofrelay F is broken at contact 2p.

The calling subscriber hangs up during metering In the event of thecalling subscriber replacing his receiver when a metering impulse hasjust been produced by the relay chain Z, YIY4, the transfer to rapidmetering cannot take place before the termination of this meteringimpulse since the first impulse of the more rapid succession can only betransmitted when the first and These relays cannot energize, however,because contact 88113 of relay Y3 which only energizes, however, in thecase of metering during a call is opened. This releases when after relayY4 has energised the circuit for relay Z is broken by the opening ofcontact 30114 and the locking circuit for relay Y4 is broken by contact8911a. When the second metering impulse is terminated, that is whenrelay Y4 has released on account of the short-circuit established atcontact 99112 the assessor magnet energizes over contact M4 14 so thatnow relays SI and YI become energized when contact 8911a closes. andthus commences the first impulse of the more rapid succession. Thefurther operations then take place in the manner described above.

What is claimed is:

1. In an automatic switching system, means for extending connections toa plurality of zones, zone determining means in said system operated inaccordance with the zone to whicha connec tion is extended fordetermining the particular metering impulses to be transmitted for aconnection, and blocking means operated after the zone determining meanshas been operated for preventing the further extension of the connectionunless said zone determining means is operated to a proper position todetermine said impulses.

2, An automatic switching system as claimed in claim 1, in which saidblocking means is also efiective for preventing any further influencingof the zone determining means.

3. An automatic switching system as claimed in claim 1, in which theblocking means includes two relays, one of said relays operated toprevent the further extension of a connection, and the other of saidrelays is affected by said zone determining means to either prevent orallow the operating of said one relay.

4. In an automatic switching system, means for extending connections toa plurality of zones, zone determining means in said system having aplurality of contacts each associated with the transmission ofparticular metering impulses in accordance with the zone to which avconnection is extended, blocking means for preventing the furtherextension of a connection, and other means operated through any one ofsaid contacts to render said blocking means ineffective.

5. An automatic switching system as claimed in claim 4, normally closedcontacts associated with said other means, and means including saidclosed contacts for rendering said blocking means efiective.

6. An automatic switching system as claimed in claim 4, in which theoperation of either of said blocking or other means is effective toprevent further influencing of the zone determining means.

7. An automatic switching system as claimed in claim 1, a test relay insaid zone determining means, said relay tested as to its ability tooperate after the determination of said impulses and said blocking meansthereafter rendered effective or ineffective in dependence upon saidrelay.

8. In an automatic switching system, means responsive to impulse trainsfor extending connections to a plurality of zones, zone determiningmeans in said system for determining, in accordance with the zone towhich a connection is extended, the particular metering impulses to betransmitted for that connection, devices in said determining meansresponsive to said impulse trains and testing means associated therewithrendered effective responsive to a particular setting of one of thedevices for determining whether the connection may be completed.

9. An automatic switching system as claimed in claim 8, means affectedby said testing means for preventing the further extension of aconnection, and other means associated therewith for rendering the sameineffective at times when one of said devices does not have a particularsetting.

10. An automatic switching system as claimed in claim 8, wherein a faultin said device having a particular setting renders said testing meansineffective and prevents further extension of a connection.

11. In an automatic switching system, means for extending connections toa plurality of zones, a zone determining device in said system operatedin accordance with the zone to which a connection is extended fordetermining the particular metering impulses to be transmitted thereto,said device including a circuit for maintaining potential on said meansthrough a series of inductances and a series of relays each associatedwith certain of said inductances, and means for operating said relays insequence responsive to one of said metering impulses to transmit impulses by varying the effective inductance of said circuit.

12. In a metering'arrangement associated with means responsive toimpulses transmitted for extending connections, a plurality of controlleads for determining a number of metering impulses to be transmittedperiodically over a connection, a stepping switch, having access throughcertain of the bank contacts thereof to said control leads, responsiveto a particular impulse train for rendering a particular control leadeffective, other contacts of said switch engaged simultaneously withsaid certain contacts, a relay operative in a circuit including one ofsaid other contacts for preventing further extension of a connection ontermination of a particular impulse train, and another relay associatedwith said control leads operated in a circuit including said particularcontrol lead to render said first relay ineiiective.

13. In a metering arrangement associated with means responsive to aseries of impulse trains for extending connections, a plurality ofcontrol leads for determining a number of metering impulses to betransmitted periodically over a connection, stepping switches, havingaccess through certain of their bank contacts to said control leads, oneof said switches responsive to a particular impulse train of the seriesfor rendering a particular one of the control leads effective, othercontacts of one of said switches rendered effective by certain impulsetrains of the series, a relay operative in a circuit including one ofsaid other contacts for preventing further extension of a connection ontermination of a particular impulse train, and another relay, associatedwith said control leads, operated in a circuit including said particularcontrol lead to render said first relay ineffective.

HANS J LURK.

